Many electronic circuits utilize more than one supply level to improve speed and operation of the circuits, while mitigating power consumption. For example, a circuit may have portions operating at a first level and other portions operating at a second level. Additionally, the circuit may have varied modes that utilize different power levels, such as sleep modes, low power modes, and the like. Some examples of varied voltage levels are 5 V, 3.3 V, 1.8 V and the like.
The varied voltage levels can be provided in a number of ways. For example, separate power sources can be utilized to provide the varied levels. However, this can be costly in terms of die space and complexity. As another example, a level shifter can be used to select or provide varied levels from a single power source. Thus, varied levels of 2.5 V and 5V can be provided using a level shifter with a single 5V power source. However, these approaches can be costly to implement and may suffer reliability issues.